Selective spin-state switch and metal-insulator transition in GdBaCo2O5.5

By C. Frontera, J. L. Garc'ia-Munoz, A. Llobet, M. Aranda. 2002

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Ultrahigh resolution synchrotron diffraction data for GdBaCo 2 O 5 . 5 throw new light on the metal-insulator transition of Co 3 + Ba-cobaltites. An anomalous expansion of CoO 6 octahedra is observed at the phase transitionon heating, while CoO 5 pyramids show the normal shrinking at the closing of the gap. The insulator-to-metal transition is attributed to a sudden excitation of some electrons in the octahedra (t 6 2 g state) into the Co e g band (final t 4 2 g e 2 g state). The t 5 2 g e 1 g state in the pyramids does not change and the structural study also rules out a d 3 x 2 r 2 /d 3 y 2 - r 2 orbital ordering at T M I .

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/b0fea95b3f3ac07f13423e3ad5cdc38e615ced73